Kenny MacAskill came under fire from Labour, the Liberal Democrats and the Tories after a 20-minute statement to the Scottish Parliament setting out his reasons for releasing Abdelbaset Ali Al Megrahi who is dying from prostate cancer.
But he insisted the controversial move, which caused outrage in the US, was the correct decision.
The Libyan, convicted of murdering 270 people in the 1988 Pan Am airline bombing over Lockerbie, returned to Tripoli on Thursday night to “a hero’s welcome” after being freed on compassionate grounds.
The reception has led to the Duke of York scrapping a trip he had planned to Libya believed to have been intended for next month.
Buckingham Palace said: “There are no plans for the Duke of York to visit Libya.”
In London Prime Minister Gordon Brown faced growing pressure to break his “deafening silence”.
Shadow defence secretary Liam Fox branded Brown “cowardly” for refusing to say whether he thought it was right to free Megrahi.
Liberal Democrat leader Nick Clegg said it was “absurd and damaging” for Brown to remain silent.
However, a spokesman for Brown insisted: “It was and it remains a decision for the Scottish Justice Secretary.”
Yesterday’s emergency session of the Scottish Parliament, which saw MSPs called back a week early from their summer recess, lasted for just over an hour.
Members of the public queued up outside for a seat and the public benches were full by the time MacAskill rose to speak.
After the statement, Scottish Labour leader Iain Gray asked: “Does he understand how much his decision has angered the silent majority in Scotland? Does he understand how ashamed we were to see our flag flying to welcome a convicted bomber home?”
Scots Tory leader Annabel Goldie said: “I want to make clear the decision to release Mr Megrahi was not done in the name of Scotland or in the name of this Parliament, or in my name.”
Scottish Liberal Democrat leader Tavish Scott said: “Doesn’t Kenny MacAskill’s comment on the need for Scottish compassion mean no prisoner, however bad their crime, will ever have a request turned down?”
MacAskill said he had acted properly, that the decision was his alone, and that it had been reached in line with Scottish procedures.
The Scottish Parliament questioning took place against a background of undiminished criticism of the decision to free Megrahi.
Despite the criticism, two Labour voices spoke up for MacAskill.
Former Labour first minister Henry McLeish became the first prominent Labour politician to back the decision when he told the BBC: “This is probably the right decision made for the right reasons.”
And in yesterday’s Holyrood exchanges, Labour MSP Malcolm Chisholm commended a “courageous decision which is entirely consistent with both the principles of Scots law and Christian morality”.